Nolan Worstell1, Joshua Weatherston1, Pratik Krishnan1, Ishan Bajaj1, M.M. Faruque Hasan1, Hung-Jen Wu1
1Dept. Chemical Engineering, Texas A&M University, USA
Most biochemical processes in the intracellular environment begin by membrane recruitment, protein transport from 3-D space to a 2-D membrane surface. This is achieved by multivalent binding interactions that synergistically combine weak affinity monovalent lipid-protein binding events to increase binding affinity and specificity. These multivalent binding events are essential for protein recognition, but the mechanism is poorly understood. To better understand the multivalent binding mechanism, quantitative analysis of multivalent membrane recruitment onto the cellular membrane is essential. We have developed a nanocube sensor coupled with complex reaction analysis to quantitatively explore the multivalent binding mechanism. The nanocube sensor is surrounded by a lipid bilayer that possesses the same physical and chemical properties as cell membranes. This biomimetic surface then enables the label-free detection of multivalent binding interactions by observation of the absorption spectra shift of the localized surface plasmon resonance (LSPR) peak. This biosensor works with a standard laboratory plate reader for high-throughput binding kinetic analysis. The simple protocol (“mix-and-then-detect”) allows any end users to perform the analysis in their own laboratories. We have successfully explored many essential multivalent binding events, including Cholera toxin-glycolipid and Shiga toxin-ganglioside interactions. Moreover, we have introduced a complex reaction analysis technique to analyze the rich kinetic data acquired by the high-throughput lipid array and model the binding cooperativity among multivalent binding proteins, ligands, and accessory molecules. This technique can also be used to study other biomolecule adhesion, including nucleic acid and pathogen adhesions.